Polyesters are widely used to manufacture textile fibers and in resins to form bottles and containers. For example, U.S. Pat. No. 5,945,460 to Ekart et al. describes one method of using scrap recycled polyester in a polymerization reactor and blending the recycled polyester with virgin polyester; and, in U.S. Pat. No. 6,506,853 which issued to J. F. Duan, a method for making an IPA/PET copolymer is described. The teachings of these patents are incorporated herein by reference. Copolymers of this type are, commonly used resins to make throw away bottles and containers. These thrown away bottles are part of a substantial ongoing collection and recycling process where the bottles are shredded or chopped and used as feed material in extrusion processes. While this recycling process is highly desirable from an environmental and waste disposal point of view, the copolymer content of the polyester used in various recycled bottles is not the same resulting in an uneven and erratic IPA content in products extruded from the recycled material. This limits the use of the recycled resin to principally bottles, or other products where a wide range of physical properties can be tolerated; but, such variations in the co-monomer content have certain drawbacks when used for fiber production.
Accordingly, it is one object of the present invention to provide an IPA/PET fiber product having improved and consistent properties.
Among the inconsistent properties of prior art fiber from recycled resin are lack of level or uniformity in dyeing, unreliable moisture control, and excessive pilling. One method for level dyeing of synthetic material including polyester is described in U.S. Pat. No. 4,101,274 to Helmut Beutler et al. which mentions the use of leveling agents including dispersible polyester.
Accordingly, it is another object of the present invention to provide polyester fiber products that can be dyed with improved uniformity of color with reduced dependency on leveling agents or similar additives.
In the prior art one use of polyester products has been to make a fabric for garments that will wick or remove moisture away from the body. Garments and fabrics which do this are described in U.S. Pat. Nos. 4,954,398, 5,297,296, and 6,093,491. In these patents and other prior art publications, shaping of the fiber to provide moisture transport channels has been one way of achieving the desired moisture transfer.
One more object of the present invention is to provide a polyester fiber that does not require shaping or change of cross-section of the fiber in order to transport moisture.
The foregoing and other objects are achieved by the invention described below.